Extragalactic abstracts - IRSA - California Institute of Technology
Extragalactic abstracts - IRSA - California Institute of Technology
Extragalactic abstracts - IRSA - California Institute of Technology
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Spitzer_Approved_<strong>Extragalactic</strong><br />
Mar 25, 10 16:24 Page 565/742<br />
Spitzer Space Telescope − General Observer Proposal #50753<br />
Infrared Search for Hidden Active Galactic Nuclei<br />
Principal Investigator: Michael Werner<br />
Institution: JPL<br />
Technical Contact: Varoujan Gorjian, JPL<br />
Co−Investigators:<br />
Daniel Stern, JPL<br />
Kieran Cleary, JPL<br />
Stephen Murray, Harvard Smithsonian Center for Astrophysics<br />
Christine Jones, Harvard Smithsonian Center for Astrophysics<br />
William Forman, Harvard Smithsonian Center for Astrophsyics<br />
Ryan Hickox, Harvard Smithsonian Center for Astrophysics<br />
Varoujan Gorjian, JPL<br />
Science Category: AGN/quasars/radio galaxies<br />
Observing Modes: IrsStare<br />
Hours Approved: 19.7<br />
Abstract:<br />
In 1982 Elvis et al called attention to a pair <strong>of</strong> galaxies with AGN−like x−ray<br />
emission but no AGN features in their visible spectra [referred to here as<br />
XBONGS]. Since then, deep x−ray surveys [Moran et al 2002] have revealed large<br />
numbers <strong>of</strong> galaxies with these characteristics: luminous in the x−ray but<br />
without the high excitation lines, specific line ratios, or broad emission lines<br />
which characterize Type I and/or Type II AGN. Thus understanding XBONGS is an<br />
important step towards defining the accretion history <strong>of</strong> the Universe. For<br />
brevity, we continue to refer to these objects as XBONGS, while recognizing that<br />
they are not a homogeneous group, and in fact a variety <strong>of</strong> explanations have<br />
been proposed. It has been suggested that XBONGs are powered by AGN which are<br />
hidden at visible wavelengths by (i) dilution by the bright emission from the<br />
galaxy, by (ii) extinction, or by (iii) the absence <strong>of</strong> visible and ultraviolet<br />
radiation due to modifications in the character <strong>of</strong> the accretion disk which<br />
surrounds the central black hole. These suggestions can be tested by infrared<br />
observations, so we propose here a program <strong>of</strong> IRS spectroscopy <strong>of</strong> 8 XBONGs<br />
carefully selected from 26 XBONGs identified in the XBootes survey <strong>of</strong> the NOAO<br />
Deep Wide−Field Survey. We will observe the [NeV] 14.3um and the [NeIII] 15.6um<br />
lines to identify and characterize the hidden AGN in these galaxies, drawing on<br />
our published Spitzer observations <strong>of</strong> these lines in AGN with known x−ray<br />
emission. We hope to distinguish among the competing models for the XBONG<br />
phenomenon and to make an assessment <strong>of</strong> this problem as part <strong>of</strong> the legacy <strong>of</strong><br />
the cryogenic Spitzer mission.<br />
Spitzer_Approved_<strong>Extragalactic</strong><br />
Printed_by_SSC<br />
Mar 25, 10 16:24 Page 566/742<br />
Spitzer Space Telescope − Guaranteed Time Observer Proposal #86<br />
Imaging and Spectroscopy <strong>of</strong> X−ray Selected Seyfert Galaxies<br />
Principal Investigator: Michael Werner<br />
Institution: JPL<br />
Technical Contact: Varoujan Gorjian, JPL<br />
Science Category: AGN/quasars/radio galaxies<br />
Observing Modes: IrsStare MipsPhot<br />
Hours Approved: 23.5<br />
Abstract:<br />
In present unified schemes, dust plays a major role in determining Seyfert<br />
types, with Seyfert 1’s being less obscured and Seyfert 2’s being more obscured,<br />
but both with the same underlying energy generation mechanism, an accretion disk<br />
around a supermassive black hole. We have chosen to study a group <strong>of</strong> Seyferts at<br />
two wavelengths that are least affected by dust obscuration: x−rays and<br />
infrared. Our sample is a mix <strong>of</strong> Seyfert 1’s and Seyfert 2’s which have been<br />
observed in the x−rays, for which we will obtain IR spectra with all IRS<br />
modules, and photometry at 25 and 70 microns with MIPS. By comparing the<br />
characteristics <strong>of</strong> these two penetrating data sets we will be able to constrain<br />
better the role <strong>of</strong> dust in the nuclei <strong>of</strong> these active galaxies, especially the<br />
large column densities (>10^25 Hydrogen atoms per cm^2) derived from x−ray<br />
observations.<br />
Thursday March 25, 2010 xgal_covers.txt<br />
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